Ladies’ night at Tiger Tiger is known as “the place to pull” in the West End of London: four floors of dining and drinking, dancing and DJs until 3am.

But the ambulance summoned there shortly after 1am yesterday was dealing with a young man who had fallen over, cracked his head and wasn’t going to have much success on the dancefloor.

It was as the paramedics left the club on Haymarket that one of them noticed the pale green Mercedes parked directly outside. The interior of the car seemed to be filling with smoke.

The crew members immediately called London Ambulance Service control room, which notified Scotland Yard. The first police officers to arrive on the scene saw enough to persuade them to sound a major alert.

On the back seat of the Mercedes were propane gas cylinders and a large number of petrol canisters that seemed to be emitting vapour. There also appeared to be boxes of nails and other items scattered around the seats. The officers realised quickly that they were dealing with a roughly assembled, improvised bomb.

Initial assessments are that a small detonation would ignite the petrol, causing an intense fire the heat of which would explode the gas canisters and send shrapnel and nails flying in all directions. It was crude but, in the words of Scotland Yard’s first statement of the day, “potentially viable”. And potentially lethal.

By the time that Tiger Tiger’s bewildered customers began to make their way from the back of the building to safety, bomb disposal units were already at work outside the front door.

Alastair Paterson, 25, who was in the club, said: “It was around 1.30am when the music was turned off and the lights went up. Doormen and other security staff were escorting people out of the building. I have never seen a place empty so quickly. It was like a ghost town. We were all led out, through a side alleyway.

“An ambulance had been called to treat a drunk clubber outside the building when they noticed smoke coming from the car and alerted the police. At first when I saw the car and the smoke coming out from the back we all just thought it was a drunk driver. It was only when they wouldn’t let us back in to get our bags and coats that we realised that something more serious was going on. It was then that people started thinking it was a terrorist attack.”

Miles Batty, 33, one of the club’s DJs, said: “I could see the bomb disposal robot in the road inspecting the car. One of the customers had come up to me and told me what was going on. Then a doorman came downstairs. The key was getting people out from the top floors. When people left, the cordons were already up.”

Whatever the remote cameras on the robot relayed back to its controllers, they were satisfied that a bomb disposal officer should move in to attempt to dismantle the detonator.

The method by which the car bomb was to be fired, thought to be similar to the mobile phone-activated detonators seen in the Madrid train bombings of 2004, was identified and dismantled by hand, preserving vital evidence for the waiting scientists from the Forensic Explosives Laboratory.

Deputy Assistant Commissioner Peter Clarke, head of Counter-Terrorism Command, paid tribute to the “courage and skill” of the explosives officers. He said that they had “manually disabled the device, and in so doing not only did their action prevent damage and injury to property but [they] have given us opportunities to gather a great deal of forensic and other evidence from the vehicle”.

Gordon Brown, who woke early to begin his second morning as Prime Minister, was told immediately of events at Haymarket overnight. If Mr Brown had hopes of dominating the news agenda, al-Qaeda was determined to show him that it had other plans. There had been “no predictive intelligence” of the first al-Qaeda vehicle bomb in Britain. But it was something that everyone involved in Britain’s counter-terrorist machinery had been expecting. Earlier this year Sir Ian Blair, the Metropolitan Police Commissioner, issued a warning that “vehicle-borne weaponry is the greatest danger that we can face”.

Counter-Terrorism Command confirmed recently that it had been conducting security spot checks on tanker vehicles entering London for more than a year.

Fears about al-Qaeda were heightened when it emerged that a second car bomb, in another Mercedes, had been left primed just a few hundred yards from the Tiger Tiger device in Cockspur Street, near the offices of the Department of Culture, Media and Sport. This Mercedes was ticketed for illegal parking at 2.30am and an hour later a tow truck arrived to remove it to the local car pound in Park Lane.

As the vehicle was off-loaded, an operator noticed a strong smell of petrol and it was decided not to take the car into the underground car park for safety reasons.

It was only later, as news of the first incident in the Haymarket emerged, that the parking attendants at Park Lane made a connection and called the police.

The crude nature of the devices also carried echoes of two other terrorist conspiracies recently foiled in Britain.

Two months ago a group of men who had links with the July 7 bombers were jailed for planning to detonate a huge fertiliser bomb, possibly in a vehicle, at a shopping centre or nightclub. Surveillance of the gang overheard its members discussing an attack on “all those slags” in the Ministry of Sound nightclub in London.

But the closest model for the attack appeared to be that laid down by Dhiren Barot, now serving 30 years in prison, in a document entitled The Gas Limos Project, which he prepared for and presented to al-Qaeda’s leadership in Pakistan.

Barot, a Hindu convert to Islam and veteran jihadi, envisaged packing three stretch limousines with gas and other fuels and blowing up prominent buildings in London.

In his document, Barot wrote: “Place 12-13 full-size cylinders in each limo. A few should be sprayed yellow because yellow cylinders in the West signify toxic gas.

“This will aid to spread terror and chaos when the emergency service teams arrive. Underneath and around the cylinders generously place some loose pieces of charcoal (that have been pre-soaked in petrol). Place a 10-litre petrol can containing nails next to each cylinder.”

Barot envisaged setting off the cocktail of lethal ingredients with grenades or pipe bombs. He concluded: “Estimated casualties to be hundreds, if the building collapses.”

Barot’s cell aimed to park the car bombs in underground car parks beneath major hotels and office buildings. There was a further reminder of that scheme yesterday afternoon as explosives experts examined the suspect vehicle in the Park Lane underground car park.

The Dorchester Hotel, one of Barot’s targets, was briefly evacuated. There were further alerts during the day in Fleet Street and also in Tooley Street, just across the Thames, and extra security checks were made on vehicles at the Wimbledon tennis tournament.

— Additional reporting: Sean O’Neill, Steve Bird, Patrick Foster, Michael Evans

“Terrorist attacks in the UK are a real and present danger”
National Counter-Terrorism Security Office

“Britain faces a serious and continuous threat”
Gordon Brown

“While we can minimise the risks, we can never completely eliminate them”
Jacqui Smith

“Carnage”
Police prediction of the potential damage

“There could have been significant injury or loss of life”
Deputy Assistant Commissioner Peter Clarke

“These things happen”
Jack Straw

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